Growth factors in the collateral circulation of chronic total coronary occlusions: relation to duration of occlusion...

Despite extensive animal experimental evidence, there are few data on the relation of growth factors and collateral function in humans.

In 104 patients with a chronic total coronary occlusion (CTO; >2 weeks' duration), collateral function was assessed invasively during recanalization by intracoronary Doppler and pressure recordings. A collateral resistance index, R(Coll), was calculated. Blood samples were drawn from the distal coronary bed supplied by the collaterals and from the aortic root to measure basic fibroblast growth factor (bFGF), monocytic chemotactic protein-1 (MCP-1), transforming growth factor-beta (TGF-beta), placenta growth factor (PlGF), and tumor necrosis factor-alpha (TNF-alpha). The bFGF concentration in the collateralized artery was higher than in the aortic root (34+/-20 versus 18+/-14 pg/mL; P<0.001). bFGF was highest in recent occlusions (2 to 12 weeks) with the highest R(Coll). Higher collateral concentrations were also observed for MCP-1, TGF-beta, and PlGF, but without a close relation to the duration of occlusion. TNF-alpha was not increased in collaterals compared with the systemic circulation. MCP-1, PlGF, and TGF-beta were significantly increased in small collaterals with the highest shear stress. Diabetic patients had lower bFGF and higher MCP-1 levels than nondiabetics.

In CTOs, the continuous release of bFGF into collaterals showed a close relation to the duration of occlusion and collateral function, which underscores its therapeutic potential. Other factors influencing growth factor release appeared to be shear stress for MCP-1, TGF-beta, and PlGF and the presence of diabetes.